This invention relates generally to evaluation of articles positioned on a body, and in particular to a computer-based simulation system for evaluating articles with a comfortable fit to a human body across a body's range of motion and subjected to various use conditions.
Clothing and other articles which are used on the body should interface with the body so as to be comfortable when the user is stationary, such as when standing or sitting, and also during movement, such as when walking. One ideal article would fit against the user's body with suitable contact pressure sufficient to hold the article in place but without constricting the skin or degrading comfort. This is challenging because of the wide variation in body shapes of potential users and the various potential material properties the article may have can affect the interactions between the body and the article.
Body fit is often influenced by size or shape of the article but is also characterized by less tangible descriptions such as moving with the body or being less noticeable while wearing. Fit depends on an initial position of the article relative to the body and any subsequent user movements which shift relative positions, deflect the article's shape, and/or cause the article to apply greater or lesser pressure against the user's body. Comfort is influenced by multiple factors including the shape of the user's body, mechanical properties of the underlying bodily tissue, the shape and size of the article, mechanical properties of the article, and interactions between the article and any other adjacent articles. These properties are highly three-dimensional in nature and are not easily analyzed when designing a new article or improving an existing article's configuration.
In addition to comfort, articles may have functional requirements which aggravate the difficulty in finding a satisfactory article configuration. For example, absorbent products for personal care and/or personal protective use, such as disposable diapers, disposable pants, medical garments, feminine hygiene products, incontinence products, medical drapes, facemasks and barrier products, should fit well against the body not only for comfort, but also for effectiveness in absorbing bodily exudates without leakage. A product of this type that fails to fit well may apply undesired pressure against the user's body or contain gaps or openings that can cause the product to fail functionally. For example, as a person stands up from a seated position or walks, his or her thighs may squeeze a diaper or other absorbent product and may deform it in a manner that results in leakage of fluid.
The development of new or improved products that avoid these problems is complex due to the large number of potential shapes, contours, sizes, component materials, and material distributions. The advent of newer materials with an improved range of compressive and elastic properties and less bulk emphasizes a need to understand the complex interactions between the body and the product. Unfortunately, the process of identifying an acceptable or optimum combination of design parameters which is functionally effective and comfortable across a normal range of user body shapes and motions is time consuming and becomes a substantial expense.
New products are typically defined with initial reliance on historical data, and are subsequently tested both in physical laboratories and in wearer use. Such tests use sample products in conjunction with human test subjects or physical models of test subjects. Unfortunately, physical testing has many limitations. The sample products can be constructed only with readily available materials and construction techniques. Even if materials and construction techniques are available, the time and expense of assembling a variety of sample articles for testing can be substantial and potentially prohibitive. Testing procedures are limited to available and acceptable physical tests. These tests, when available, are limited by their physical nature including safety issues, which are especially applicable as they relate to human-use testing. Moreover, the resources needed for human-use testing can be enormous and the time required for that testing could delay market entry. One can go through considerable time and expense to find out that a material or product idea will not work.